This study will examine multiple cause mortality differentials among various demographically and geographically defined sub-populations of the total U.S. population for the years 1969 and 1974. Previous demographic studies of mortality have suggested the necessity in going beyond studies of the underlying causes of death to the investigation of multiple causes of death. Research of this type has seldom been conducted on the entire U.S. population because of the unavailability of appropriate data for individuals and because of a lack of appropriate methodological procedures. The investigators will demonstrate the appropriateness of certain categorical data models applied to the parameters of pattern of failure elimination life tables, as a methodology to study multiple causes of death. The research will focus on the linkage of conditions in mortality, especially of the linkages between chronic morbid conditions and the age specific variation of these linkages among the relevant sub-populations. A determination will be made of the change in such condition profiles for the period 1969-1974 to determine if changes in the associations of diseases can help explain recent changes in death rates for certain causes.